[ b a c k ]

/********************************************************************
 * bs.c is a program that demonstrates byte stuffing.
 *
 * Completed: 9:50 AM 2/9/01
 * Author:    William Martin boneshakerbike@hotmail.com
 *******************************************************************/

#include <stdio.h>
/*********************************************************
                VARIABLES
**********************************************************/
char string1[25] = {1, 'H', 'i', ' ', 27, 'w', 'o', 'r', 
                   'l', 'd', ',', ' ', 1, 'I', ' ', 'a', 
                   'm', ' ', 'h', 'e', 'r', 'e', 4, 4};
char string2[25];
char packet[28];
int index1 = 1, index2 = 0;
/*********************************************************
                FUNCTIONS
**********************************************************/
void packetStuff(void *str);
void packetUnStuff(void *str);
/*********************************************************
                MAIN
**********************************************************/
int main(void){
	printf("\n"
    "Hello and welcome to a byte stuffing exercise."
     "\n\nSince you cannot type non printable characters"
     "\nfrom the keyboard this exercise will use the"
     "\ncharacter string "
     "\n\n\"[soh]Hi [esc]world, [soh]I am "
     " here[eot][eot]\" "
     "\n\nFor soh you will see ==> %c"
     "\nFor esc you will see ==> %c"
     "\nFor eot you will see ==> %c"
     "\n\n", 1, 27, 4);
   printf("Before stuffing: %s\n", string1);
   packetStuff(string1);
   printf("After stuffing: %s\n", packet);
   packetUnStuff(packet);
   printf("After un-stuffing: %s\n", string2);
   return 0;
}
/********************************************************************
 * packetStuff is a function that takes a message in the form of a
 * string and for every soh, eot, and esc another sec is added in
 * front to provide packet stuffing.
 *
 * Completed:    7:41 AM 2/9/01
 * Dependencies: (global) variable packet is modified
 * Input:        string of characters
 * Output:       void
 * Sample Call:  packetStuff(string);
 *******************************************************************/
void packetStuff(void *str){
	packet[0]= 1;
   for(int i = 1; i < 23; i++){
     	if(string1[i] == 1 || string1[i] == 4 || string1[i] == 27){
        	packet[index1] = 27;
      	index1++;
         packet[index1] = string1[i];
         index1++;
      }else{
      	packet[index1] = string1[i];
         index1++;
      }
	}
   packet[index1] = 4;
}
/********************************************************************
 * packetUnStuff is a function that takes a message that has been
 * stuffed and unstuffs it.
 *
 * Completed:    7:50 AM 2/9/01
 * Dependencies: (global)variable string2 is modified
 * Input:        string of characters (stuffed)
 * Output:       void
 * Sample Call:  packetUnStuff(packet);
 *******************************************************************/
void packetUnStuff(void *str){
	for(int i = 0; i < 30; i++){
     	if(packet[i] != 27){
        	string2[index2] = packet[i];
      	index2++;
      }
	}
}

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